Published: July 4th, 2021
Zebrafish embryos/larvae develop externally and are optically transparent. The bioaccumulation of microplastics in fish at early life stages is readily assessed with fluorescently labeled microbeads.
As a new type of environmental pollutant, microplastic has been widely found in the aquatic environment and poses a high threat to aquatic organisms. The bioaccumulation of microplastics plays a key role in their toxic effects; however, as a particulate, their bioaccumulations are different from many other pollutants. Described here is a feasible method to visually determine the accumulation and distribution of microplastics in zebrafish embryos or larvae using fluorescent microplastics. Embryos are exposed to different concentrations (0.1, 1, and 10 mg/L) of fluorescent microplastics with a diameter of 500 nm for 120 h. It is shown in the results that microplastics can bioaccumulate in zebrafish embryos/larvae in a concentration-dependent manner. Before hatching, strong fluorescence is found around the embryonic chorion; while in zebrafish larvae, the yolk sac, pericardium, and gastrointestinal tract are the main accumulated sites of microplastics. The results demonstrate the uptake and internalization of microplastics in zebrafish at early life stages, which will provide basis for better understanding the impact of microplastics on aquatic animals.
Since first synthesized in the 1900s, plastics are widely used in various fields, resulting in rapid growth of global production1. In 2018, approximately 360 million tons of plastics were produced worldwide2. The plastics in the natural environment will degrade to fine particles due to chemical, physical or biological processes3. Generally, fine plastic particles <5 mm in size are defined as microplastics4. Microplastics are also engineered for specific applications, such as microbeads from cosmetic products5. As near-permanent contaminants, micro....
Adult zebrafish are originated from the China Zebrafish Resource Center (Wuhan, China). The experiments were conducted in compliance with the national guide "Laboratory Animal Guideline for Ethical Review of Animal Welfare (GB/T35892-2018).
1. Embryo collection
The distribution and accumulation of fluorescent microplastics are shown in Figure 1 and Table 1. No visible fluorescence is observed in the unexposed group (control). However, an accumulation of fluorescence is found surrounding the chorion after exposure to different concentrations of microplastics (24 hpf). Green fluorescence is also detected in larvae, and the fluorescence levels appear to increase in a concentration- and time-dependent manner. The yolk sac, pericardium,.......
According to the guideline on the protection of animals used for scientific purposes, such as EU Directive 2010/63/EU, animal ethics permission is not mandatory for an experiment with early life-stages of zebrafish until the stage of being capable of independent feeding (5 days post fertilization)17. However, best welfare practice is important for optimizing the use of zebrafish, and, for example, the humane methods of anesthesia and euthanasia should be of concern. Ethyl 3-aminobenzoate methanesu.......
|Green fluorescently labeled polystyrene beads
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